Telephone system.



F. G. UNGER.

TELEPHONE SYSTEM.

APPLIGATION FILED MAR. 1. 1911.

ylli Bamm Apr, 9, 19112.A

ii sa. 1

TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Apr. 9, 1912.

Application filed March 1, 1911. Serial No. 611,584.

To all whom t may concern? Be it known that I, FRANK C. UNGER, a citizen of the United States, residing at St. Louis, Missouri, have invented a certain new and useful Improvement in Telephone Systems, of which the following is a full, clear, and exact description, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to telephone systems, and particularly to local battery or magneto telephone systems such as are used in small towns and in the country.

ln a magneto telephone system each subscribers telephone is provided with a generator or ringing machine that the subscriber has to turn or actuate in order to operate his line-drop att-he central exchange which notifies the central opeiator that the subscriber desires to talk to another subscriber. After the conversation is completed the subscriber who originated the call alsov generator or ringing ma' has to operate the chine on his telephone so as to operate the clearing-out drop at the central exchange which notities the central operator that the conversation is completed.

(lne object of my invention is to provide a. local battery telephone system that comprises a generating device or machine at the central exchange for operating lthe subscriberys line-drops and the clearing-out drop. and a separate and distinct generating device or machine for ringing the bells of rthe subscribers telephones, thereby producing a system in which the means used for signaling and supervision on the cord circuit is separate and distinct from the means used to operate the other signaling devices of the system, the signaling genera, tor being preferably so constructed that its current is dissyiichronous with the bells of the subscribers telephones so that it will not interfere with same or with other devices oii the circuit.

Another object is to provide a local battery telephone system that comprises impedance coils or other suitable resistance devices bridged across the cord circuit and which are preferably incorporated with the clearing-out drop at the central exchange, said impedance coils or resistance devices being so designed that their transformer action will not cause the receivers of the subscribers? telephones to receive any current in case said receivers are thrown into a divided circuit or become affected by any inductive disturbance on the line.

Another object is to provide a system of the. character above referred to in which the resistance devices that are bridged across the cord circuit have their middle contacts grounded so that any accumulation of static or induced electricity on the line will readily pass through the resistance devices and .then to the earth through a condenser which is shunted around the signaling generating device, thereby causing the lines to be free from noise, from static accumulation and induced charges on the telephone circuit while talking, owing to the fact that the static accumulation and induced charges pass readily to the ground.

Another, object is to provide a telephone system'wliich is so designed that current of a pulsating or alternating character can be used for operating signals over very long lines. However, I do not wish it to be understood that my invention is limited to the use of a pulsating or alternating current for signaling purposes for direct current could i `be used for this purpose.

Another object is to provide a telephone system which is so designed that the signaling current affects both line wires equally and in the same direction and at the same time, thereby overcoming the possibility of the signaling current affecting the receivers of the subscribers telephones.

Another object is to provide a telephone system comprising two impedance coils or other resistance devices bridged across the line circuit so as to cause the line-drop at the central exchange, rather than the bell of a subscribers telephone, to operate in case either side of the line is grounded accidentally, it being preferable to use a double wound drop, which is so designed that there will be no transformer action between the two impedance coils which might cause the bells of the subscribers telephones to ring in case'same are thrown into a divided circuit by a ground on the line.

Another object is to provide a telephone system of the type referred to which is so designed that a signal can be transmitted to the line-drops over one or both limbs of the circuit and over a third conductor or the ground, thereby enabling both sides of the line to be used as one circuit and thus cnt-ting down the resistance of the circuit by one-half which is a very decided advantage on long lines.

Another object is to provide a telephone system of the 'type referred to. that comprises condensers which separate one side of the cord circuit from the other, thereby permitting the talking current to` pass through the condensers and preventin the signaling cur= rent from passing throng the condensers so that the clearing-out drops are caused to op-4 erate individually.y

Another object is to provide a telephone system having a circuit which is so arranged that meansare provided for transmitting different fre uencesl at the same time, whether they e pulsating or alternating, o that one will not interfere with theoth r. And still another object is toprovide a telephone s stem having condensers ,at the subscribers instruments which will prevent either the bells or receivers from belng' affected in case the subscribers bellsl or receivers are thrown into a divided circnitzor caused to become part of a divided circuit.

Figure 1 of the drawings is a-cliagrammatic view of la telephone system constructed in accordance with mv invention; Fig. 2 is a diagrammatic view illustrating another method from that. shown in-Fig. y1 for increasing or varying the inductance in the circuit and also adding capacit to the circuitso that the current "from t e signaling l generator will rise and falll gradually; and

Fig. 3 is a -diagrammatic view illustrating a double wound drop which' can be used in place of the resistance devices-in Fig. 1 that are bridged across the line-circuit and connected to they line-drops.

illustratesthe perferred form of my invention, A and B designate the telephones of twosubscribers, and-C designates the operators telephone at the central exchange. The central exchange is. provided with suitable signals such, for example, as line-drops 1 and 2, vfor'the subscribers AA and B, 'respectively, and also clearing-out drops 3 and 4 for both sides of the cord circuit which notify the central operator that the Asubscribers. have completed their conversation and hung up their receivers. A signaling lmachine 5, which may consist of a generatin machine or pole-changer, either man.- ua ly or mechanically operated, is arranged at the central exchange, and resistance devices 6, preferably impedance coils built on v large heav iron cores, vare connected in series with t e-circuit of said signaling ma-l chine 5. A condenser 8 is arranged across the circuit of said signaling generator, and

said resistance devices are so arranged that the inductance of said devices and the capacity of the condenser 8 in the generating circuit causes the current of the generating Referring to Fig. 1 ofthe drawings which -which said plugs coperate. Each suberator'f 5 at the central exchange being machine 5 to rise and fall gradually. Sepa-v rate and distinct resistance devices 7, preferably'impedance coils, are bridged across the cord circuit at the central exchange, and the signaling generator 5 is connected in series with the clearing-'ont drops 3 and 4 and with the middle tap of the resistance devices 7. By arranging the impedance' coils or resist ancedevices 7 in pairs across the cord circuitl divide the signaling currents into two equal parts and cause same to pass-through the two windings in opposite directions, the two paths having about' the same resistance. Consequently, the two limbs of the circuit are arranged in parallel for signaling currentsand. in series for talking or telephon- 1ng. y

The reference characters 9 and 10 designate, respectively, the key of the listening circuit and thel ringing key vat the centralexchange, and said central exchange is also provided with a ringing machine 11 which is separate and distinct from the signaling generator 5. The ringing machine 11 may be of any preferred construction but it is preferab y so designed that it will ring only the bells of the subscribers telephones. 'I also prefer to arrange condensers 12 across the cord circuit at the central exchange'so as to cause the low frequency signaling current to 95 operate the clearing-out drop only on that side of the cord circuit on which the si al .is transmitted. Thus, when called-subscriber B takes his receiver ofi' its supporting hook the clearing-ont drop 4 at the central exchan e will operate. The central exchange is, o course, provided with the usual plugs 13 and 14 for the subscribers A and B, respectively, and contacts 13al and 14a with scribers telephone is provided with line springs L R andA a grounded contact S, which s rings are normally separated, and the hooi? switch 15 is provided with an insulated part N that A,closes the contacts L, R and S for an linstant when the hook 'switch moves ineither direction and thus causes a ground to be thrown on either or both sides of the line for an instant, the signaling gengrounded. Condensers 16 and 17 are arranged in the circuits off/'the subscribers telephones, as shown iii/Fig. 1, which offer a very high resistance/to vlow frequency cnrrent; and resistance devices -18, preferably l impedance co/ils, are also arranged across the line circuityas shown in'Figs. 1 and 3. Consequent y, if a ground is thrown o'n either side o the Iline, the line-drop or clearingout drop at the central exchange, rather than the snbscribers bellI or receiver, will be operated, owing to the fact that the accidental ground. causes the bell or receiver of the subscribers telephone to be thrown into a divided circuit. This is a very desirable fea- 130 ture in a telephone system for if there is a ground on either side of the line the subscribers can converse as the current from the signaling generatordoes not interfere with the talking circuit.

In Fig. 2 I have illustrated another way of increasing or varying the inductance in the circuit and also varying or adding capacity to same, the circuit shown in said figure comprising inductance coils 6%* arranged in series in thesignaling generating circuit and condensers 8a arranged across sai circuit., the advantage of such an arrangement being that enough impedance coils and condensers can be provided. to cause the current to rise and fall gradually.

Having described the general const-ruction of my improved telephone system, I will now describe the operation of same. If the subscriber A wishes to talk to the subscriber B he removes the receiver of his telephone from its 4supporting hook'thereby causing a ground contact to be made over either or both limbs ofl the circuit. This causes a current to pass through either one or both of the reslstance t devices 18 and through the subscriber As line-drop at the central exchange. The operator then inserts the plug 13 in the coperating contacts 13 and then opens the listening 9, the insertion ofthe plug 13 in the coperating contacts 13a causingthe resistance devices ,18- and line-drop to be disconnected from the circuit. After ascertaining the number of the subscriber to whom A desires to talk,

. the operator closes the listeningk key 9 and inserts the plug 14 between `its coperating contacts 14a, at the same time. ringing the subscriber Bs bell by means of the ringing` key 10. When the cal-led-subscriber -B removes the receiver of his telephone from its supporting hook, the clearing-out drop 4 associated with the calling side of thecord circuits will operate and thus notify the central operator that the circuit is taken and that the conversation has started. When the subscribers have completed their conversation and hung up the receivers on .their telephones the clearing-out drops 3- and 4 associated with the different sides of the cord circuit, will be exposed or operated by the current which the signaling generator 5 produces in the cord circuit.

' The impedance coils and condensers ar-v ranged in the signaling circuit in the manner described, oppose any rapid change in the strength of the current so that the cur- A rent wave or sine wave assumes a smooth wave form with no peaks. This is a veryv desirable feature in a telephone system because the current will not cause any inductive disturbance in the subscribers receivers while they are talking.

In a systemV of the-character above described, the non-interference of the voice coils of said resistance devices being currents and signaling currents` is not dependent upon such a wide difference in frequencies but it is due to the fact that the signaling current flows over both sides of the circuit in parallel and in the same direction, using the ground or a third conductor as a return, the voice currents being conned to the metallic circuits and' Howing through the two sides of the circuits in series. This non-interference is also due partly to the fact that the condensers 16 and 17 at the subscribers telephones allow the telephone currents or voice currents to pass through them but do not allow or offer very high resistance to the low frequency signaling current whenv the receivers are caused to be in a divided circuit on account of a ground on one side of the line.

Having thus described my invention, what I claim as new and desire to secure by'Letters Patent is: i

1. A local battery telephone system comprising an' alternating current generating machine at the central' exchange for operating the line-drops and clearing-out drop, and a separate an distinct generating device for operating the bells of the subscribers"telephones.-

2. A telephone system having a signaling generator and means for preventing the induced current from said generator from affecting the receiver. of a subscribers telephone in case said receiver is thrown into a divided circuit.

3. A telephone system having resistance devices vbridged across the cord circuit, the

on separate cores so as to reduce their transformer action to a minimum, and condensers arranged in the line circuit so as to prevent the receivers of the subscribers telephones from becoming ai'ected by any inductive` disturbance on the line in case said receivers are thrown into a divided circuit.

4./A telephone exchange system comprising a signal-generating device at the central exchange, resistance devicesv bridged across. the cord circuit, and a condenser arran ed across the circuit of said signal-generating device.

5. A telephone exchange system, comprising a grounded signal=generating device arranged at the central exchange, resistance devices ybridged across the cord circuit and having their middle contacts grounded, and a condenser arranged across the circuit of said signal-generating device.

6. In a telephone system, condensers in the subscribers circuits and resistance devices bridged across the' line circuit for causing the linedrop at the central exchange,

rather than the bell of a subscribers telel 7. In a telephone system, resistance deinstruments and constructed in such a manner that they prevent either thebells or receivers of said instruments from becoming affected 1n case said bells or rcelvers are thrown into a divided circuit.

8 A telephone exchange system having a signal-generating machine arranged at the central exchange, resistance devices arranged in the circuit of saidv machine, and a condenser arranged across said circuit.

. 9. A telephone exchange system having a signal-generating machine arranged at the central exchange, resistance devices arrangedin the circuit of said machine, a condenserv arranged acrosssaid circuit, and a signal for the central operator arranged in series in the circuit of said machine.. A

1'0. A telephone exchange system having an operators signal at the central exchange, a generating device or' machine arranged in series with said signal, resistance devices arranged in series in the circuit of said.4

machine, and a condenser arranged across the circuit of said machine.

l11. A telephone exchange system comprising a pair of resistance devlces bridged across the cord circuit at the central exchange so asv to divide the signaling currents; an operators signal at the central exchange, a signal-generating machine connected in series with said signal and With the middle tap of said resistance devices, and a condenser arranged across the circuit of lsaid signaling machine;

12. A telephone exchange system corn-A prising a pair of resistance devices bridgedl devices arranged in the circuitof said generating machine.

13. A telephone system, comprising a plurality of condensers arranged in the line circuit of each subscribers telephone so as to prevent said telephone from vbecoming affected by inductive disturbances on lthe line, and resistance devices. arranged across the line circuit.

14. A' telephone exchange system, com# prising condensers arranged in the circuits of the subscribers telephones, resistance de- -vices arranged across the line circuit, linedrops at the central exchange incorporated .with said resistance devices, a ringing generator at the v central 'exchange for operl ating the bells of the subscribers telephones,

land a separate signal-generating machine at the central exchange for operating the signals at the central exchange. x A

' 15. A telephone exchange system, comprising condensers arranged in the circuits 'of the subscribers telephones, resistance de- A vices arranged across the line circuit, linedrops at lthe central exchange incorporated with said resistance devices, a ringing generator at the central exchange for operating lthe bells of the subscribers telephones, a separate signal-generating machine at the 'central exchange for operating-the signals at the centralexchange, clearing-out drops at the central exchange, resistance devices bridged across the cord circuit at the central exchange, the"clearingout drops being connected to the middle tap of said lastnamed resistance devices, and a condenser arranged across the circuit of said signal- -generating machine.

In testimony whereof l hereunto ahx my signature in the presence of two Witnesses, this twenty fifth day of February 1911.

FRANK C. UNGER.

Witnesses: v

laLLs L. CHURQH, GEORGE BAKEWELL. 

